The present invention relates generally to MR imaging and, more particularly, to a flexible RF coil assembly capable of conforming to a patient's shape.
When a substance such as human tissue is subjected to a uniform magnetic field (polarizing field B0), the individual magnetic moments of the spins in the tissue attempt to align with this polarizing field, but precess about it in random order at their characteristic Larmor frequency. If the substance, or tissue, is subjected to a magnetic field (excitation field B1) which is in the x-y plane and which is near the Larmor frequency, the net aligned moment, or “longitudinal magnetization”, MZ, may be rotated, or “tipped”, into the x-y plane to produce a net transverse magnetic moment Mt. A signal is emitted by the excited spins after the excitation signal B1 is terminated and this signal may be received and processed to form an image.
When utilizing these signals to produce images, magnetic field gradients (Gx, Gy, and Gz) are employed. Typically, the region to be imaged is scanned by a sequence of measurement cycles in which these gradients vary according to the particular localization method being used. The resulting set of received NMR signals are digitized and processed to reconstruct the image using one of many well known reconstruction techniques.
It is desired that RF receiver-coil arrays be made light and flexible so that all of the coils can be positioned close to a patient and that patient comfort may be maintained while fitting an RF receiver-coil array to a variety of patient sizes and shapes. However, repeated flexing of RF receiver coils and their corresponding circuitry may alter the performance and shorten the working life of the RF receiver coils.
It would therefore be desirable to have an RF coil apparatus capable of conforming to a patient's shape while protecting the RF receiver coils and corresponding circuitry from repeated flexing.